Field of the Invention
The invention relates to an arrangement for supplying electric energy to electric traction motors in a railway vehicle and for supplying electric energy to additional electric auxiliaries for operation of the railway vehicle. Furthermore, the invention relates to a railway vehicle with such an arrangement. Moreover, the invention relates to a method for supplying electric traction motors and additional electric auxiliaries for or during the operation of the railway vehicle. The invention also relates to a method for manufacturing the arrangement and the railway vehicle.
The railway vehicle may, for example, be a locomotive. However, the invention is not restricted to this. Rather, the railway vehicle may, for example, be a train set.
Description of Related Art
Heretofore, a common arrangement for supplying electric energy to electric traction motors in a railway vehicle and for supplying electric energy to additional electric auxiliaries for operation of the railway vehicle comprised a minimum of two internal-combustion engines (in particular diesel engines), each of which is combined with an electric machine. During a so-called generator mode of operation of the electric machine, the electric machine generates electric energy, while it is driven by the internal-combustion engine. Due to this, the electric energy is available within the railway vehicle to supply electric consumers. The consumers in particular are the traction motor or traction motors that drive(s) a motion of the railway vehicle, and so-called auxiliaries, which do not immediately provide traction, but may in particular be absolutely necessary for driving the railway vehicle. Auxiliaries can in general be defined by the fact that electric energy is supplied to them from the usually present direct-current link through their own auxiliaries inverter or several own auxiliaries inverters. Auxiliaries include fans and other cooling devices that cool the internal-combustion engines, the traction motors and/or other devices necessary for driving operation (e.g. power converters). Furthermore, driving operation requires a brake system, and, therefore, brake system components such as air compressors are auxiliaries. Other examples of auxiliaries are the railway vehicle's fire extinguishing system, electronic devices for controlling the operation of the railway vehicle, battery chargers, heatings which are at least temporarily necessary for driving operation such as front window heating and/or lighting systems in the driver's cab. Optionally, those electrical installations may be distinguished from the auxiliaries which are provided merely for passenger comfort, e.g. lamps in the vehicle compartments. Such electrical installations on trains are usually supplied with electric energy from the so-called train connector. The train connector is connected to the direct-current link not via any of the auxiliaries inverters, but via a dedicated inverter.
It is known that the electric energy generated by the electric machines is fed into a direct-current link via at least one rectifier (hereinafter: generator rectifier, because alternating current generated by the generator is rectified). Typically, several inverters are connected to the direct-current link which generate the alternating current of the desired voltage level or within the desired voltage range which is required for the consumers and systems connected at the AC voltage side. In addition to the inverters, DC converters may be provided at their DC voltage side and/or transformers at their AC voltage side to alter the voltage level. Other power converters may also be connected to the direct-current link, either directly or indirectly. Moreover, other electric consumers, e.g. electrical installations provided for passenger comfort, such as lighting, air-conditioning and information systems, may be supplied with electric energy from the direct-current link, in addition to the auxiliaries mentioned, e.g. via an inverter other than one of those used for auxiliaries necessary for driving operation.
For example, the following devices are connected to the direct-current link: several traction motors of the railway vehicle via one or several traction inverters; a train current connector via an additional converter or directly; auxiliaries necessary for driving operation via an auxiliaries inverter. Moreover, additional converters may be connected to the direct-current link, e.g. for the purpose of converting into heat any excess energy which is supplied to the direct-current link when the railway vehicle is braked. An example of such an arrangement is described in WO 2009/077184 A1.
In cases where more than one internal-combustion engine exists and at least one electric machine is coupled with the internal-combustion engine, it is possible that just a part of the existing electric machines generates electric energy, while simultaneously another part of the electric machines is operated as motor(s), in particular to drive the assigned internal-combustion engine in no-load operation. The advantage of this is that the supply of fuel to the internal-combustion engine can be switched off. However, alternatively, it is also possible that at least one of the internal-combustion engines is running only at a low rotational speed and hence the electric machine(s) assigned generate(s) just a low amount of electric power, which e.g. does not, or not considerably, contribute to the electric power supplied to the direct-current link.
Accordingly, the presence of more than one combination of internal-combustion engine and machine enables part-load operation of the railway vehicle, i.e. operation in which not the maximum of the possible electric power is required. Therefore, part-load operation means a mode of operation in which the mechanical power of just a part of the internal-combustion engines is sufficient to provide the necessary electric power. In addition to reducing the fuel consumption of the internal-combustion engines, another advantage of part-load operation is lower exposure of the surroundings to noise. For instance, four internal-combustion engine/machine combinations may exist, each of which can, preferably, be operated independently of the other combinations, either in no-load operation or at the optimal performance point. Optionally, more than two modes of operation can be set for each combination, e.g. operation at medium power of the electric machine operated as a generator in addition to the two modes of operation mentioned.
With respect to the further possible features of an arrangement with more than one internal-combustion engine/machine combination, reference is made here in particular to the international patent application number PCT/EP 2012/052705, filed on Feb. 16, 2012. In particular, the entire content of that application is hereby incorporated into this present application.
Electric auxiliaries installed in addition to the electric traction motors and supplied with electric energy from the direct-current link in particular comprise such auxiliaries which are necessary for driving operation of the railway vehicle as mentioned above. Accordingly, if the auxiliaries inverter, via which these auxiliaries are electrically connected to the direct-current link, fails or has to be switched off, driving operation cannot be continued. This is the case although the direct-current link and the supply of the traction motors from the direct-current link may still be functioning.